From a book by Mary Ann Curran Environmental Life-Cycle Assessment, McGraw-Hill 1996:
EPI is a scalar quantity where the total effect of the environmental impacts (by emissions or consumptions per unit of product) is calculated from a weighted average of the impacts. It is based on 13 impact categories, within three main groups:
- Resource depletion parameters-resource effy., 4 parameters
- Health impact parameters-health quality, 2 parameters
- Ecological parameters-ecological quality, 7 parameters